1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to devices and methods for implanting a prosthetic aortic valve in a patient.
Aortic valve replacement procedures have historically been performed in opened chest, stopped heart procedures where the native valve is removed and a synthetic or biologic tissue valve is sutured in its place. Although highly successful, the need to open the chest and the potential side effects of cardiopulmonary bypass needed to sustain the patient while the heart is stopped have spurred the development of less invasive transcatheter and endovascular procedures performed on a beating heart.
While such transcatheter and endovascular procedures have enjoyed success and are being increasingly utilized, the nature of the valves and limitations of the implantation protocols still limit widespread adoption. In particular, the need to deliver the valves in a compressed configuration stowed in access catheters or other delivery devices has made the transcatheter and endovascular valves less adaptable than are prosthetic valves used in open surgical procedures. In particular, present transcatheter and endovascular valve designs are often not useful in patients having bicuspid aortic valves, degenerated bioprosthetic valves, aortic stenosis associated with aortic aneurysms, aortic dissections, unusual or variant anatomies or in procedures replacing previously implanted prosthetic valves.
Patients suffering from different valve-related conditions can require valves having quite different geometries. For example, patients suffering from aortic stenoses may have quite different requirements than those having a concomitant aneurysm in the ascending aorta. Patients may also have different anatomies which would in some cases benefit from placement within the valve annulus or in other instances benefit from placement above the annulus and/or above the native or bioprosthetic valve leaflets. Moreover, the replacement of previously implanted prosthetic valves may dictate even different requirements on the prosthetic valve structure, as discussed below.
The feasibility of transcatheter or endovascular aortic valve implantation within previously implanted bioprosthetic aortic valves has recently been demonstrated. Degeneration of originally implanted bioprosthetic aortic valves can occur through a number of mechanisms, including calcification. Although such “valve-in-valve” (VIV) implantation has shown promise, hemodynamic complications from implantation of currently available transcatheter valves within small bioprosthetic valves can be problematic. A principal problem is the reduction in valve area which occurs when a valve is implanted within the base or frame of the previously implanted valve. Another important problem is the deformation of the implanted valve by the calcified diseased valve. Such deformation can result in leaks around the implanted valve or through the implanted valve leaflets which will not align properly when the stent surrounding the leaflets are squeezed in a smaller size than intended or squeezed away from its intended circular shape.
Thus, it would be desirable to provide improved transcatheter and endovascular aortic valve designs which can be used in a variety of replacement procedures including both native aortic valve replacement and replacement of previously implanted prosthetic valves. Such aortic valves should be adaptable and configurable to conform to different patient anatomies and to treat patients having different conditions, including aortic stenoses, aortic insufficiency, aortic calcification, aneurysms in the sinus of valsalva or ascending aorta, and any other condition which might require native or prosthetic valve replacement. Such aortic valve designs should be adaptable for use in natural valve replacement as well as for valve-in-valve implantation, where in both cases the valves provide superior hemodynamic performance. The present invention will at least in part meet these objectives.
2. Description of the Background Art
Percutaneous aortic valve-in-valve replacement is described in Wenawest et al. (2007) Catheter Cardiovasc Intery 70:760-764. Prosthetic heart valves adapted for supra-annular implantation are described in Turing (2004) Multimedia Manual of Cardiothoracic Surgery doi: 10.1510/mmcts.2004.000646; and Vergnet (2009) Eur J Cardiothoracic Surg 35:970-976 Patents of interest include U.S. Pat. No. 6,582,462; U.S. Pat. No. 5,411,552; U.S. Pat. No. 6,893,460; U.S. Pat. No. 6,730,118; U.S. Pat. No. 7,018,406; U.S. Pat. No. 4,451,936; U.S. Pat. No. 5,489,297; U.S. Pat. No. 5,562,729; U.S. Pat. No. 6,315,791; U.S. Pat. No. 6,440,164; and U.S. Pat. No. 7,025,780. Other publications of interest include Walther et al. (2008) Ann Thorac Surg 85:1072-1073; Azadani et al. (2009) Ann Thorac Surg 88: 1864-1870; Azadani et al. (2010) Interact Cardiovasc Thorac Surg 11:70-77; Azadani et al. (2009) Ann Thorac Surg 88:1857-1863; Dwyer et al. (2009) J Thorac Cardiovasc Surg 138:1227-33.